The field of the invention is countersinking tools, specifically, tools for making countersunk openings in hollow metal door frames.
Hollow steel door frames are attached to the walls adjacent the doorway by means of wall anchors. In order for the wall anchors to hold the door frame securely in position and to provide a professional appearance, the wall anchors should be inserted through openings drilled into the door frame to a sufficient depth that the wall anchors are flush with the door frame. To do this, the drilled opening should be countersunk in the direction and to the depth the wall anchor is to be inserted.
Sometimes the door frame comes from the factory with the countersunk holes already drilled, but usually not. If there are no factory-drilled countersunk openings, workmen have to drill and countersink the openings at the worksite. At present there is no tool available for doing this. Workmen usually use either a steel rod or a balpeen hammer to drive the wall anchor into the door frame. This is a difficult process that does not yield uniformly satisfactory results.